Digital rights management (DRM) is a technology used to protect and control the distribution of contents, such as music files, video files, and other contents. The DRM may, for instance, be used to limit the distribution and access of content to a particular mobile phone. Here, a user may purchase content stored in a memory card and, to bind the content with a mobile phone, the mobile phone stores a secret. In DRM, content is encrypted with a cryptographic key, whereby the cryptographic key can also be used to decrypt the content. A cryptographic key used to decrypt the content may be derived from the secret stored in the mobile phone and the content can therefore be accessed based on the cryptographic key.
A limitation with storing the secret in the mobile phone is that if the user changes to a different mobile phone, the content will not be accessible by this mobile phone because it does not include the secret. As a result, there is a need to further improve the protection of content.